This invention concerns a device for automatic rewinding of material delivered in sheets in heliographic and similar machines, particularly for heliographic machines for textile industries.
It is well-known that in the field of textile industries, it is necessary to reproduce patterns of considerable length (as long as 10 meters and more) and then to utilize the copies of the patterns themselves for cutting the fabric to be made into clothing.
Therefore, it is necessary, in the heliographic machines employed in this sector, to achieve the rewinding of very long sheets of originals and the copies obtained from them, upon delivery, into rolls which are then unloaded from the machines themselves.
There are heliographic machines currently in use which are equipped with two horizontal rollers for rewinding the two delivered sheets (original and copy), such rollers being connected to a suitable means of power in order to keep them rotating continuously.
The rewinding of the delivered sheets, however, does not take place automatically, insofar as it is necessary to wind the ends of said sheets, as they are delivered from the machine, by hand around the aforementioned rollers for a short while until they are able to grip the latter which, only from this moment on are able to continue the winding without the need for manual operations. Upon completion of the reproduction operation, two rolls will have formed upon the aforementioned rollers and will then be unloaded by temporarily removing the rollers themselves from the heliographic machine.
With this known method however, apart from the inconvenience of manual intervention, another very big problem is encountered and consists of the fact that the operator must very rapidly start winding the two separate sheets, as they are delivered simultaneously from the machine; a fact which calls for special skill and which sometimes causes damage to the sheets to be wound.
Attempts have been made to eliminate this manual intervention by means of automatic winding devices consisting of flexible arched elements fitted in correspondence with the delivery area of the sheets to be rewound.
These arched elements have the task of gradually rolling the sheets as they are delivered from the heliographic machines, however the results achieved have been rather poor due to the fact that the sheets are inclined to crawl (espcially when they present a certain thickness) or do not slide as they form the coils, consequently, they either roll up incorrectly or do not roll up at all.
Moreover, in order to unload the rolls, it is necessary to hold the aforementioned flexible arched elements wide apart, deforming them considerably and resulting in frequency damage to the said elements and in undesirable crushing of the rolled sheets.